Wallace began by challenging Miller with a quote Friday from Trump, who conceded: “I didn’t need to do this. But I’d rather [build the wall] much faster.”

Wallace turned to Miller: “How does that justify a national emergency?”

Miller cited a “crisis” at the border with an “increasing number of people crossing the border.”

“Let’s look at the facts,” Wallace responded.

He pointed to statistics highlighted on a screen that illegal border crossings were less than 25 percent of figures from 19 years ago. He also noted that nearly 90 percent of illegal drugs coming across the border enter via ports of entry, where walls don’t — and won’t — exist.

Miller responded that no one, including the administration, knows who is dodging detection. “You don’t know what you don’t know,” he said.

Wallace also pressed Miller, who considers himself a staunch defender of the Constitution, to provide a single example of another president invoking national emergency powers to get money that Congress denied him through the appropriations process.

Wallace noted that of the 59 times the 1976 National Emergencies Act was invoked by a president, only two were for military construction funds, which Trump plans to use: during the Gulf War and after 9/11.